Method of making artificial teeth



Marcl; 30, 1943. H. M.v THORNTON :a1-'AL 2,314,957.

METHOD oF MAK c- L- y A INVENTORS Y y HEM? M. TV /P/vTo/y VVA HND E ET ORNEY Mmhso, 1.943.` MTHQ'NTONfTAL 12,314,957

- `METHOD QF'MAKING ARTIFIC'IAL TEETH.'

INVENT HENRY M. THORNTO y[4 Y I u Y BY AND CHARLES D/ETZ .Y

ATTQRNEY- v March 30, 1943 .n S. 4 Y Y T 3 HJ L T En A L 2. n n 8 6 m w m F R 2.21 R G m o m M H K An .nuv l T M e Z M. w m 5 a w XM Y INVENTORS v HENRY M. THORNTON BY AND 'Es L1/157:2` l

' i ATTORNEY March 30, 1943. H. M. THORNTON ET AL 2,314,957 u Filed April 15, 1941 D/ETZ /CU TTRNEY- Patented Mar. 30, 1.943V

. l f 2,314,957 l UNITED STAT-.ES ilATl-lflii"lfl FFICEQ Mirrnonor mxzsiqtrrrlil'Al-TEE' l I I nem-y M. 'riirnton andl Cim-les DietaKYi-k, f assignors to The Dentists Supply Company of @New York, New York, N. Y.,

NewYork K -K a'corporation of 'K Wasserman-1115,19,seriai'NoQssacsi i if *somma (ctie-55.1)

This .invention relates to'lartiiicial teeth, and more particularly to artificial teeth in which the distribution of colors andrtranslucence simulateI the appearance of natural teeth which have surface stains, abrasions, sub-surface color distribution, and* variations in translucence' within the teeth. K p f lHeretofore artificial teeth have been composed in principal part of two materials, one a relativelytranslucent enamel material, and the other a relatively opaque body material.l For the purpose of more closely simulating natural teeth,- itfis -proposed touse novel .placements of these two materials and also to employ additional materials oi' different and contrasting colors and varying the manufacture of artificial teeth.

A primary object lof the present invention is 'to provide artificial teeth which closely resemble `natural teeth. i

A further object of the invention is to provide a, process for producing artificial teethwhich when placed in the mouth will closely resemble tufts,'enamel lamella, vand `clentine designs might Vbe accurately reproduced in repeated mouldings.

enamel facing of an individual 'toothu *This die may be arcuate onrits external surface. This arcuate surface may be provided with one or more depressions or with one or more elevationsfor both, at desired areas. vIn these depressions we .,area of the lingual side'of said'iacing.: Thesev adjacent natural teeth, and inthe case lof entire dentures,- will give. the appearance of natural According to the invention, :the process comprises-the use of a multi-part vmould which, in

making anterior teeth for example, may consist of the labial surface forming mould member, the lingual surface forming member, and the shader members, which latter may coact with either the labial surface forming member or the lingual surface forming member. K

In the'aforementioned Clapprpatent allowance of the shader member will appear in relief united i lected areas.

' terial originally placed inthe depressions oi' the f was made for the use of onlyvtwo materials, body and enamel, and no provision was incorporated therein whereby the visible irregularities of natural teeth such as gnarled enamel, terminal branches of dentinal tubules, enamel spindles,

may place .a body material" or enamel 4material or a material of a different color and .composif tion than the body material or enamel material. The relatively translucent enamel or .facing material isthen placed in the labial forming' mould Amember and the shader mould .member when applied thereto will vat one'and the same time shape the lingualsurface of the enamel material into 'a .generally concave mass increasing in thickness from the gingival to the incisal lportionof the toothand'deposit `the materiall which had been previously vplaced `inthe depressions of the shader mould member dies Vat thepre-selected assembled mould members are'pressed, orxvibrated and subjected to heat so v4thatbwhen .the

shader member is removed from the labial form-b ing mouldmember.: the biscuited facing. will 1re.-

mainr in the labial iormingmouldmemberaand the material previously placed in the depressions to the lingual side ofthe facing at thepre-sev K Or course,` any number of materials different from the body material or enamel material or from each other in .translucency coloranti composition may be placed iriI the various depressions' in the dies ofthe shader member.

. -After "the iirst biscuiting operation body material is applied to the lingual forming mould member and may also be applied to the labial' forming rvmould membery sufficient to form the balance of the tooth. These two mould members are then assembledpressed and heated to form a complete biscuited' 'tooth.The tooth is then permanently vitriiied or hardenedand'the mashader member will'appear through the relatively translucent enamel on the labial side thereof.

Along with, or in place of depressions, the shader mould memberl may be provided with elevations on its dies'which -will thiny out pre'- selected areas ofthe enamel 'or facingmaterial or at the lingual thetooth. f

in the labial forming mould memberv when appliedthereto. As previously described, relatively translucent enamel material is applied to thek labial forming mould member and the shader member is applied thereto, vibrated or pressed, heated, land the biscuited facings which remain i in the labial forming member after the shader member is removed, will contain thinned-out g areas corresponding to the designs'in relief on the dies of the shader member. To these areas may be applied material the same `all-.the body material or the enamel material, or different v from the body material'or enamel lmaterial in f both color and composition. n After the ilrst biscuiting operation body material is applied to the lingual forming mould member and may be applied to the labiall formi ing mould member suillcient to form the balance of the tooth. These two'mould members are then assembled, pressed and heated 4to form ay complete biscuited tooth.` Thetooth is then vitriiied` .in the case` of a porcelain tooth, or hardened in the case of a plastic tooth-and the material which was applied to the thinnedout'areas of the ybiscuited facing will be apparent when the finished ytooth is viewed on'iits labial side. The teeth of older persons. or teeth. which ,have been subjected 4to extreme incisal abrasion have theirk incisal enamel tips so worn down that `they exhibit av permanent brown or black or yellow stain whichappears at the incisal-edge surface of theincisalportion` of To simulate this. appea i' rance in artificial teeth we may' provide the shadermould member .as

where the shadery member formed the enamel or veneer portion of the tooth nrst.

In this method body material is placed in. the

gingival area of the lingual forming mould member andthe shader member when applied thereto will shape the labial surface ofv the body material into a generally convex fonn in which the incisal extent of the body thus formed terminates somey distance from the incisal edge of the tooth," except in those instances where, for the purpose of simulating natural tooth designs, it is desiredto have lobes or stripes extend to or v`near to the incisal edge of the completed tooth, and 'the shader member at the same time Awill deposit the'materal which had previously been placed in the depressions of the shader dies at the pre-selected area of the labial side of said f body portion. These assembled mould members are pressed and subjected to h'eatso that when j the shadergrmember is removed from the lingual forming mould member the biscuited body portioniwill remain in thelingual forming mould Y member andy the material previously ,placed in f the depressions of the shader mould member will described above with *a depression extending `mesially-distally all the way across the-incisal surface of the shader member or. optionally, ex-

tending over pre-selected portions. of the incisal area of the shader member, or extending gingivally from the incisal area along the -mesial and; distal sides of thev shaderfinember to any desired point, sothat effectsand designs oi' in- 'cisal discolorations and meeial-distal color effects may bev achieved by nlling in these de-I pressed kareas with suitable coloring material.

Or, alternatively, lthe shader member may bev provided'in its incisal area with raised portions which produce depressed areas in the lingual side of theenamel veneer, and-these depressedv suitably colored mav areas may be illld inwit'h terial. V

In order to simulate the `surface irregularities in the lingual incisal yarea of naturallteeth.

caused by abrasion, we may employ an elevation or elevations in the incisal areav of the above described shader member to shape `rthe lingual incisa] portion `of theenamei material vmore desired contour. To keen these depressionsopen when the lingual mould member replaces the vshader mould member. similar elevations should be provided in theincisal portion ofthe lingual forming mould member.

Another method of practicing the inventionis toy have the shadermmould member coaot with the lingual forming AVmouldfmembenin which Ivase the. body portion of the-tooth is formed nrst. The shader member. employed in this processl may'be considered to consist of dies which have a generally concave arcuate surface in which at desired areas may be provided one or more depressions or oneor more. elevations or both forforming designs :and effecting color kplacements similar in purposeto those described the shadermember.

appear in relief united to the pre-selected areas of the biscuited body portion.

After this first biscuiting operation relatively translucent enamel or facing material is applied to 4the labial formingfmould member and may be 2 applied to the incisal area of the lingual form- 'ing` mould member suillcient` to form thelbalance of the tooth;` These two mould members are then assembled, pressed and heated to form a complete biscuitedtooth. The tooth is then vitriiied or hardenedand the material originally f which remain in the lingual forming mould meinber when the shader member is removed will contaln on their labial side thinned-out areas correspending with the design in relief on the dies of To theseareas mayv be.l applied material the s amesas the body material or the enamel material, or different from the body materialor the enamel material in .color and composition. Y,

Afterrthek first biscuiting operation relatively translucent enamel material is applied to the labial lforming `mould member and mayalso be` appliedto the incisal portion-of the lingual forming mould` member, sufllcient to complete the balance of thetooth. These two mould members are thenassembled, pressed andv heated to form -a complete biscuited tooth. The tooth is then vitriiled or permanently hardened, and/the material which was applied to the thinned-out areas of the` biscuited body portion will be visible through the relatively translucent facing when the finished tooth is viewed on its labial side.

'I 'o provide stains and dlscolorations at the lingual incisal area ofthe tooth similar in purpose to those described Where the shader mould member formed the enamel portion first we may apply suitably colored material to the incisal area of the lingual forming mould member after the body portion of the tooth has been formed therein.

In this process we also contemplate that` surface irregularities in the lingual incisalareaof natural teeth caused by abrasion may be `accurately reproduced by employing `an elevation or elevations in the incisal area of the lingi'ial form- Figure 2 is a fragmentary perspective yview showing one ofthe die members orshaders used for forming the facing andloptionally receiving the different material,

` Figure 3 is a fragmentary perspective view of The drawings illustrate embodiments ofthe in modifiedshader die membe'rw'e may,employ,"'

' Figure 2s a afrsaxnentary' pianviewnra im further modified shader die member we may ein# ploy.' Figure 2a assessing-,gierig une :aj-: 1 pim urezaand i. s, Figure 39 is an `evational viewfvof a finished The mould ofFlgure 1 shows two sets of ante' f riorvupperteeth, and'representsfthecombination of a female facing mould' part il anda male facing mould pant i2. The mould part l! ,for

convenience will be referred` to""as".t`he"shader."

Shader" as hereinusedlrefers tothe mould part -v' adapted to form the lingualportion of the facing or fthe labialY portionof thefbody material as dis- "a facing forming die member adapted tof'coop Y erate with the die member of Figure..2, and in which the facingrmaterial is placed, l

Figure 4 is a fragmentary vertical sectional view taken along the line 4-4 of Figure l,

Figure 5 is a vertical sectional view takenalong the line 5--5 of Figure 4,

anguish-ea from the mould parts' assied to form the ,external surfaces ofthetooth, yFacingv as herein used refers to' thetransl-uc'ent enamel d is-V posed attnei-lapia1sideor an artificial tooth and whichfo'rrns auveneer forfthe "relatively opaquel 'body portionY of the tooth.`-f. Considering thatlthe j mould part Il` has th'e female forming depres,-

vsions il, a quantity of plastic. translucent vitreousJ orresinous forming material is first "placedf therein, yFigure 3 being illustrative'of each'of the Figures 6 to 9 inclusive are lfragmentary ,viewsV `showing a variety of designs ,which maybe formed in the die illustrated in Figure 2,

Figure 10 is a fragmentary. vertical section view showing the mould which deposits and forms the body of the tooth, applied Ato the bottom mouldof Figure 4, Figure 11 is a transverse sectional line Ii-II of Figure 13,

Figure 12 is a vertical sectional view'on theline i2|2 of Figure 13. Y

Figure 13 is an elevational view voi' a finished tooth, 1-

Figure 14 is a sectional view similar to Figure 4 showing a modification of our invention,

a Figure 15 is a vertical sectional view showing the' die member of Figure 3v applied to the upper ldie member of Figure 14,

j Figure 16 is a sectional view generally similar to Figure 10 showing a modified form of tooth,

Figure 1'1 is a view generally similar to Figure 14 but'wherein the lower diemember is of modifled form, A y Y Figure 18 is a view generally similar. to Figure lkshowing a further modified form of tooth,

Figure 19 is a vertical sectional-view of a iinished tooth formed by employing the die membersillustrated in Figure 16, .y 'e

Figure 20 is a plan View of a slightly modified bodyforming die member,

Figure 21 is a section taking along the' line 2i--2I of Figure 20, s

Figure 22 is a sectional view generally similar io Figure 14, but wherein the die members are modified, f v

Figure 23 shows a further step in applying the facing material and different material to the tooth body portion of Figure 22, Figure 24 is an 'enlarged fragmentary section similar to Figure 23, but'where'in d1ierent.ma ferial is introduced at the lingual incisal portion of the tooth,

Figure 25is a fragmentary plan view of a modied die member we may employ.

Figure 26 is a section along the line 26-26 of Figure`25,

'view on the .twelve diesI of themould shown in Figure 1. The`v mould part' I2-is provided with a facing forming partV |.4' having depressions liiherein. These `depressions I5 may be of any desired number and shape, Figures 6 to 9 inclusive showing alvariety of designs formed by the depressions. Onelrnodes of practicing the invention is toliill theidepress e sions Il with plastic vitreous forming material' or plastic resinous material different 'in color andlor composition from the fucina material-by `the us of aspatula orjthe like,"and we preferably 'conform thetop surface of saiddii'lferentma'terial .to the general-contourof facing 4forirlin'g part Yil.

The mouldparts il and ilarthen' assembled as illustrated in Figures 1- sind 1.4, and ksubjected to heat while under pressure and theffacinglfl l formed by the mould partsis thus biscuited.A The mouldpart i2 is thenfremoved and the diiferent material placed linlthe intaglio Vdesign,forlriedby the depressions II will appear in reliefjuponthe" 'concave'linguaiside` of facingA il." The design appearing in're'lief is generally indi'catedvlati'l.

A third Amould part I8 adapted to shape the body` portionof the tooth has the body forming ,de-,v pressionsy I9 `therein filled with vitreous or resinl ous fomning materiaiand the mould parts Il and v I8 are assembled as indicated in Figure"10.;- The, assembled' mould parts are thensubjectedftoja i; biscuiting operation.'A The biscuitedl tooth is then removed, cleaned, andvitrified in the' usual manporcelain orvv cure-hardened ner in the case of in the case of plastic.

The vitriiied or hardened tooth is illustrated in Figures 1 1, lf2 and 13 and the'` different material` embedded in the body material will appear through the relatively translucent `facinggll.in ,j "the form of spots, streaks and the like conformu .ing Ito the design i1 formed by shader part." 14. j It is understood 'that ythe different material may' s be selected to give a lighter or darkercolortlian the body or ena-mel material in the finished tooth, I 'and that the color effect may bevaried'for'a; given different material by altering'` the'de'pth ofthef y depressions l5.r Also, severalvdifferentmaterials,l g may be disDOSd .in different;depressionsl lieto, f further alter the markings appearing atthelabial side of the finished tooth.

Referring now to Figures 14 and l5`,`,vve have i' i illustrative, and that a variety of designs shown a-modied method yof lfoiirning the tooth illustrated inV Figures ll to 13 inclusive. In this modification, the shader mould part I4 is provided with a concave depression 36 having the design I1 formed in relief. Body forming material is deposited in depression 34 and the mould parts Il and 34 are combinedv and subjected to a .bisculting operation. Mould part 34 is then removed and the design'll will appear iat theehposed labial side of the blscuited body portion In material to conform-,to the general contour 'of the exposed surface of the body portion, and after depositing facing material in mould partvI-Ir, the moulds II and 4Ilare combined as illustrated in incisal termination of' facing forming part I4,

miegiid The design is thenmied with dinerent l Figure 15. The combined mould parts are then subjected to heat and pressure to biscuit the tooth, and the tooth is fired in the usual manner.` it will be seen that the resulting tooth 'is the same, lbut that in the first instance the facing is f 'first formed, and in the second instance. the body portion is first iiormei'i.v Of course, sufficient facing meteri'ai may be applied ie'meuid part -ii te iill the intaglio design Il formed inthe body portion rather than applying different material.

.Figuresy 6 to 9 inc 1usive, illustrate a varietyV of designs whichmay 'be employed, Flgurei `being an enlarged .bottom plan view of the shader mould "part of Figure 2,. In Figure 6`,` the facing forming portion I4 is provided with la central depression 'II and a plurality of generally oblong depressions 32. Figures 7 and 9 show a plurality of oblong depressions 33 of variable size and shape. Itis understood that the foregoing designs are metiixely o er than those indicated maybeused. ,l f r By reference toFigures 4 and 8 it will be noted that a groove.` is vprovided at `the incisal edge v`oi' facing forming party I4,land,t,his groove may have facing material applied ,th'eretoso that the facing material,- atv the incisal portionjextends above the parting line 44Y of the mould, as illustrated Vin 4. The facing material, as illustrated in Figure 10, projects above the parting line of mould 'partoII and into the depresv -sion I9 of mould part' Il, thereby preventing the body material from extending to the incisal 'edge of the tooth. If desired, groove 42 may have material different from both thefacing material and body material deposited therein so that, as

illustrated in Figure 16, the lingual incisal portion'ofV the tooth will comprisematerial 4l exo' ferent material,vor as illustrated, a'fsuiiicien-t o but extends both mesially anddistally towards the glngival end ofy the tooth to any desired `may be formed by eitherof the processes just described. Additionalmaterial may be'provided to form the design I1 and provide a tooth as Y illustrated in Figure 19, o'r such'design may be omitted as illustrated in Figure 16.

' Figure 1 7-"illustrates a'` shader mould part 4T wherein a design in intaglio indicated at 4l is provided and Vthisdesign may be filled with dit amount "of body material may be suppliedso that when mould parts 41 and Il are assembled a' design inv 'relief of body material will be formed. Facing forming material will then be applied to 'depression' Il of 'mould part I Il and when-mould parts I I and I 8 are assembled the 'relief design 48 will provide thinned-out areas in the facing material.

'i Figure 18 illustrates themanner of forming a tooth generally similar to the tooth illustrated in Figurel9'but wherein material 46'L disposed at vthe lingual incisal portion of the tooth vis extended to a greater extent towards the glngival end oi' the tooth than the material 4B. I'hus, the material 46* overlies a portion of the body material at the lingual side of the tooth, and this material maybe packed at the incisal portion tendlngfinia inesial-distal direction. Thus, in

the nnlsl'led tooth the material 40 will be Visible through the relatvely translucent labial incisal portlonoi' the tooth to give a desired' marking and color .effect at Vthe tooth incisal portion to conform to an elongated mesial-distal marking `frequently found in natural teeth. Figure 6 illustrates` a shader mould part wherein' Vgroove l 42 is omittedso that a substantially flat` surface 48 extends from the parting line to the incisal termination of the arcuate facing forming part I4; If a' shader mould partvof this type is used the facing material in mould part IVI will 4terminate alongline 45 at the incisal portion of the facing, and either facing material or different material 48 maybe packed into-the incisal end of body forming mould part Il. The Ishader t mould part of Figure 6 may be provided with a rib or elevation 50 on surface 40 which will provide arecess inv the incisal portion ofthe facing to receive material of contrasting color.

Figure '7 illustrates a shader mould part wherein a groove 35 extends not only along the of depression Il in the mould part I8 prior to 'depositing Vthe body material therein.

Referring now to Figures l1 and v23, we have shown a body forming mould part 5I, and a shader mouldpart I8 generally similar to mould parte la end u illustrated in Figure 4, but

wherein the body forming mould partl s profevided with a generally V-shaped depression 5 2, and'the shader mould part 58 has a cooperating v-shaped elevation thereon adapted to seat within depression 52, whereby when the mould parts Il and 62 are assembled, as illustrated in Figure 22, the body material will be prevented` from entering depression 52. Different material 51 may then be applied to thebiscuited body material, as previously described, and facing material will be' supplied to mould part I I, and the mould fparts II and 5I will be assembled, as illustrated in o Figure V23. The lingual incisal enamel material I6 will then be shaped by `edge I3 of mould part 5I, and will'enter depression 52 so that a slight step-formwill be imparted to the lingual side of the translucent enamel extending beyond the body material portion of the tooth,

- We' further contemplate that edge 53 of mould part 5I may be shaped to give anyk desired contour to the lingual incisal facing material, such as forming a depression or depressions therein and that after the mouldedtooth illustrated in Figure 23k is blscuited and removed from the mould such depression may be filled with colo material prior to firing the teeth.

Figure 24 again illustrates the use of the mould parts II and 5I, but in this instance,`the depression 52 is filled with material 59, different in color from the body and enamel material, prlorto assembling the mould parts il and so that in addition to the step formed at the lingual side of the incisal portion of the tooth, a narrow mesialdistal strip of material different from both the body andfacing is disposed at the lingual side of the incisal portion of thetooth. Markings of this type yare frequently found in naturalteeth, particularly the teeth of older persons.

Referring now to Figures 20, 21 and 27, we have shown a further modified body forming mould part 8| and shader mould part 80. In this case, the shader mould part may be provided with an intaglio design 1d and a shelf 1| extending from parting line 12 to a generally V-shaped groove 13. The groove 13 may be filled with material differlent from the body or facing material, and design 1&2 may have the same or a still different material applied thereto. A small amount of enamel may be deposited on shelf 1|, mould part may then have enamel applied thereto, and the mould part l l may then be assembled with shader mould part 80. After blscuiting and removal` of vshader mould part 80, the enamel deposited on shelf 1| will extend above or beyond the parting line of mould part Il, together with the different material deposited in groove 13 which will appear in the form of a V-shaped elevation. Mould part 8| is then supplied with body material, and when the Amould parts l and 8| are assembled the parting line of mould part will abut parting line 83 of mould part 8|, and the extended enamel material will rest on shelf 82 of mould part 8|. The V-shaped different material will 'extend into the body forming depression 84 provided in mould part 8 l, so that the resultant tooth will be of stepform with a mesial-distal stream of different material disposed at the lingual inclsal portion of the tooth. This step type mould permits the entire lingual incisal portion of the tooth to be made of a. material colored differently fromthe body or facing, since both groove 13 and step 1l of shader mould part 88 vmay have the same material applied thereto. Also, one material may be deposited in groove 13 and a different material may be 1applied to step 1| and eachof said materials may be different from both the facing and body m terial. Thus, with this method the resultant to h may have the entire lingual incisal portion of `a material colored differently from the boch! material or facing, the entire lingual inclsal portion of the tooth may be composed of two dierently colored materials extending in a mesialdistal direction, or the different material may be limited to a narrow strip run'ning in a mesialdistal direction at the incisal termination of the body material.

Referring now to Figures 25 and 26, we have shown a modified form of shader adapted to form the lingual surface of the facing. In this instance, the arcuate or convex surface 6 Iextends to the draft line 62 of the die at the sides and gingival end, and to a groove 63 at the incisal end. Surface 6| has a central depression 64 therein which may be filled with material either the same or different from thematerial disposed in groove 83. On each side of depression 64, ridges 66 extend from surface 6|, and when the shader is or striations. I t isvunderstcod that the'ridges 66 are merely illustrative and that any desired des'inxnay beused.. i

In Figures'-28and 29 a die member vis-sho'wn which is'provided with a single ridge 68, together n n -with a groove 88, and the ridge 68 will provide a thinned-out area in the facing, as previously described. f l

^ Figure 30 illustrates a finished tooth simulating a natural tooth having lobe` formations. Lobe formations are frequently found in natural teeth,

particularly the teeth of younger people, due to the dentine blending wlthtne enamel at the 1n-A cisal portion of the tooth in the formof rounded projections. The artificial ltooth illustrated' in Figure 30 may be formedby employing the herein described methods and having the body portion terminate incisally in the form of a rounded pro- Jection or lobe 1|which will be visiblethrough the translucent incisal enamel 12.

It will now be understood that the various designs described may be formed by applying .mate-` rial different from both the-body and facing ma-y terial, andthat the designs'may be formed by 'embedding the different material in the body material, or by embedding vthev different material in thinned-'out areas of the enamel or'facing'ma-- terial. Also, the different material may be omitassembled with mould part thinned-out areas ted and the designs may be'formed by either embedding facing material in an intaglio design in the body material, or by embedding the body material in an intaglio design in the facing material. We further contemplate that ya thin film rof decalcomania or stain, which may be of high fusingv porcelain stain, may be applied toany of the designs or depressions, suchas illustrated in Figures 6 to 9 inclusive, prior to filling' these depressions. 'with different material, facing material, or body material. Thus, it will be seen that an unlimited range of color markings, bothl as to contrasting lcolors and shape, may be supplied to artificial teeth bythe foregoing process wherein three orl more mould parts are employed'.

The above described process may be employed for forming porcelain teeth or teeth of resinous material, such as acrylic resins, styrene resins and the like. l

n will be noted that teeth may be formed with various markings and designs by utilizing different shaders with thel same facing forming mould part and the same body forming mould part |8 sothat itis only necessary to provide a shader mould part for each new design.

It will now be understood that we'have provided a meanswhereby a multi-part mould may be employed to accurately deposit a. vitreous or resinous forming -material iny prf-selected areas of an artificial tooth and of a given design whereby such'diiferent material will appear at the labial side of the* finished tooth in the form of streaks, spots, contrasting `color areas, and

the like, Also, such markings may be effected by employing lonly relatively translucent facing material and relatively*v opaque bodyfmaterial, or by applying one or more different materials in addition to the facingfand body material. Thus -a `considerable variety of rrlarkingsy and color effects may be obtained, and vat the same r time the use of a'shader mould partinsu'res a uniformity of manufacture in a tooth of particular structure which could not Votherwise be achieved. Further, the material providing the markings in a nished tooth is deposited'and formed during the moulding operation, and is deposited in a plastic, liquid or powder-like state.

Although we have shown and described preferred methods and apparatus for practicing our invention we contemplate that numerous and extensive departures may be made therefrom Without departing from the spirit-of our invention and the scope of the appended claims.

`The invention is hereby claimed as follows: 1. The method of forming artificial teeth having markings simulating the markingsof nat- `ural teeth, which comprises moulding a facing of material adapted to become relatively translucent, and concurrently moulding a design in relief at the lingual side of the facing to thicken an area of the facing, biscuiting the moulded facing and design, moulding the body portion of a material. adapted to become relatively opaque to the facing, and then hardening same whereby the thickened area of the facing will be visible labially as a design of contrasting color.

2'. The method of formingV artificial teeth having markings simulating the markings of natural teeth, which comprises moulding the body .portion of the tooth-with depressions in thel pear labially in contrasting color.

3; The method of providing color markings or designs in artificial teeth of the type having a relatively opaque body portion and a relatively translucent facing portion, said method comprising concurrently moulding the facing and a design in relief at the lingual side of the-facing, said design consisting of material different in 'color from boththe body material and facing material.' then moulding the body portion and around the diilerentmaterial to the facing portion, and then hardening same whereby the different material will appear through the facing 'as 'a design of contrasting color.

4. The method of providing color markings in artificial teeth of the type having a relatively opaque body portion and a relatively translucent facing portion, said method comprising moulding the body portion of the tooth with depressions in the labial surface thereof, filling said depressions with a fire-hardenable material in plasticA form'different in color from boththe body material and facing material, then moulding the facing portion to the body portion, and then hardening same wherebyV the different material will appear through the facing as designs in contrasting color. y

5. The method of providing color markings or designsin artificial teeth Aof lthe type having a relatively opaque body portion and a relatively translucent facing portion, which comprises concurrently moulding the facing portion and a design in relief at a pre-selected area of the facing incisal'portion, said design consisting of a heathardenable material in plastic form different in color from both the facing material and body material, then moulding the body portion to the facing portion and around said design, and

then hardening same whereby the design will be visible through the facing incisal portion as a design of contrasting color. y

6. The method of providing uniform artificial teeth having color markings by the use of a three-piece mould, said method comprising the steps of employing two mould parts for concurrently forming a facing of material adapted to become translucent when permanently hardened and depositing different material in the form of an elevated design at a predetermined area on the lingual surface of the facing, biscuiting the facing and different material, moulding a body portion of material different in color from the facing material and design material to the facing and around the design material by the use A come relatively opaque when permanently hai" ening same whereby the design will be vlslb labially through the translucent facing as area of contrasting color.

7. The method of providing uniform artificial teeth having color markings by the use of a three-piece mould, said method comprising the steps of disposing facing material in a first facing forming mould part, disposing different material in an intaglio design in a cooperating facing formingmould part, assembling the mould parts and applying heat and pressure to concurrently form a biscuited facing and an elevated design of different material on the lingual surface thereof, applying body material to a third mould part, assembling the first and third mould parts and subjecting the mould parts to'.

heat and pressure to forma biscuited tooth with the different material embedded in the body material, and then permanently hardening said tooth whereby the different material will be visible Iabially through the facing as a design of contrasting color.

8. The 'method of providing uniform artificial teeth of the type comprising a relatively translucent facing, a relatively opaque body portion, and having color markings visible at the labial aspect of the tooth, said method comprising steps of providing a first mould part adapted to form the labial surface ofthe facing, a second moul part adapted to form the lingual surface of"th facing having a. relatively small intaglio desig in the forming surface, and a third mould par adapted to form the lingual portion of the tooth, disposing plastic facing material in the first mould part, disposing different material in the design of the second mould part, whereby the derent material-will be substantially flush with the forming surface thereof, assembling the first and second mould parts and applying heat and pressure to concurrently form a biscuited facing and an elevated design of different material on the lingual surface thereof, separating the first and second mould-parts, whereby the facing re-' mains in the rst mould part, disposing body material in the third mould part, assembling the first and third mould parts and subjecting the mould parts to heat and pressure toform a biscuited tooth with 4the different material embedded in the body material, then separating the first and third mould parts and removing the biscuitedftooth, and then permanently hardening said tooth whereby the different material will be visible labially through the facing as a design of contrasting color.

HENRY M. THORNTON.

CHARLES DIETZ.'- 

